The instant invention is an apparatus and method for maintaining bearing chamber integrity in structures commonly referred to as a hub. Of particular concern is the hubs found in most industrial machines used in pulverizing, grinding, sanding, deburring, grinding, polishing, or the like applications where the hub may be subjected to an adverse environment. Such hubs are subjected to an environment of water, lubricating oil, grinding dirt and dust which might be microscopic, or most any other abrasive material that is used in the process. The environment surrounding the hub can result in premature wear of metals due to the abrasive nature but is especially problematic to bearings once the abrasive materials contact the bearing. The same abrasive material that is used in the particular grindings, polishing or the like process can quickly destroy the bearings once the abrasive materials come in contact with the bearings.
The hub, as used throughout this disclosure, includes a bearing chamber that has roller bearings, races of the like assemblies to allow free rotation of the hub assembly in relation to the axle. As with any friction producing components, it is imperative that the bearings are lubricated in order to prevent premature wear. Typically, grease is used which liquefies during hub rotation for use in lubricating the bearings. The grease is sealed within the bearing chamber by use of a seals positioned along an inner side surface of the hub, and a bearing cap positioned along an outer side surface of the hub. The seals are used to prevent liquified grease from escaping the hub joint.
The integrity of the seals is critical to prevent loss of grease. Absence of a lubricant can quickly lead to catastrophic failure of the bearings causing hub disengagement of the axle, which can result in assembly loss and the associated dangerous scenario of property damage. For instance, a grinding device that fails can quickly damage the item being worked upon beyond salvage, damage the sanding grinding belts beyond salvage, place the operator at risk, and result in downtime for repair of the equipment.
A bearing that is used in grinding can carry a heavy load which will quickly heat up a bearing that is not properly lubricated. Should the bearing fail, the bearing and race will typically disintegrate with a likely result of the hub detaching from the axle. In certain operations, the bearing may be subject to external pressures that may include air, water, or lubrication fluid pressure. Should there be a failure of the hub seal, the pressured air or fluid is then forced into the hub carrying with it the materials removed during the grinding operation, the ideal material for immediate destruction of the bearings. In addition, should the materials that enter the hub include moisture, bearing disintegration is greatly enhanced since rust forming on the axles surface will operate to destroy the replacement bearings with very short use.
In light of the above numerous attempts have been made in order to prevent loss of bearing lubricant. Many prior art hub devices are designed to maintain a pressurized grease within the hub. U.S. Pat. No. 4,524,917 discloses the use of bearing assembly that operates under pressure to form air seals to keep out dust and abrasive material. However, the teaching is to place the air to the outside of the seals in an effort to push contaminants away from the seal. The disclosure maintains the use of a pressurize oil lubricant for the bearings.
U.S. Pat. No. 3,609,066 discloses the use of a lubricant pump to supply pressurized lubricant to bearings.
U.S. Pat. No. 4,981,182 discloses a sealed rotary drill bit having an inner seal and an outer seal with a circumferential seal gap there between which is filed with a lubricant. Pressurized gas is carried by passageways pass through a restrictor that has a controlled dissipation to wash away drilling debris.
Current pressurized systems can result in an excess amount of lubricant being injected into the hub which results in a waste of lubricant should a leak occur. A leaking seal can cause the entire work area to become contaminated and the lubricant can contaminate the work product. In a conventional lubricant pressurized system, lubricant may be pumped in on a continuous basis with the lubricant leaking through the seal breach. In a conventional non-pressurized system, lubricant may be pumped in only when the operator deems it necessary. For instance, an operator may check a hub before starting a work project and insert grease into the hub. Once the hub reaches its operating speed, the grease liquefies and may easily escape a breached seal. Should the operator introduce a cooling liquid, the lubricant may be drawn through the seal with the uneven temperatures and the cooling liquid can be contaminated.
The environmental impact of disposing a contaminated lubricant is well known. The operator must clean the cooling liquid of the lubricant for the expulsion of grease into a conventional drain that will have a cumulative negative impact on the environment. Should the water be expelled without cleaning, even a few drops of oil can result in extensive contamination.
Thus, what is lacking in the art is a pressurization system that verifies bearing chamber integrity.